Current transformer



June 2, 1931.

R. HEINTZ CURRENT TRANSFORMER Filed March 12, 1930 Patented June 2, 1931 UNITED STATES PATENT OFFICE RALPH M.'HEINTZ, OF PALO ALTO, CALIFORNIA, ASSIGNOR T HEINTZ & KAUFMAN, LTD.,-OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF NEVADA CURRENT TRANSFORMER Application filed March 12, 1930. Serial No. 435,099.

This invention relates to current transformers, and particularly to transformers for use with high frequency measuring instruments, such as those required for measurel ment of current in radio transmitting systems. "An object of the invention is to provide a transformer whose ratio of transformation may readily be adjusted.

Another object of the invention is the pro- 3Z0 vision of a transformer which will-maintain itself in permanent position and adjustment. Still another object of the invention is to 2 provide a transformer which may be coupled with a circuit without the necessity for open- "1 ing said circuit.

A further object of this invention is to pro- 7 vide a transformer having few parts and which is easily constructed and applied.

The invention possesses numerous other objects and features of advantage, some of which, with theforegoing, will be set forth in the following description of my invention. It is to be understood that I do not limit my- "'self to this disclosure of species of my inven- -tion, as I may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawings: "Figure 1 is an end elevation of the trans- H former of this invention. One method of 0 connecting an instrument to the transformer is'shown diagrammatically in this figure.

Figure 2 is a sectional view, taken on the line 22 of Figure 1.

-Figure 3 is a view similar to Figure 1,

' -showing diagrammatically a second method -of connecting an instrumentto the transformer.

' Figure 4 is an end elevation of a modified form of the transformer, this modification '-be'ingprimarily adapted for portable or temporary use.

Figure 5 is a sectional view of the transformer shown'in Figure 4, the plane of sec- "-tion"being indicated by the line 5-5 in Figure 4;

{Mi mary. -In'F-general termsit comprises a disk \Vhere the transformer is intended for portable or temporary use, the disk is preferably divided diametrically, and the parts thereof are held together by the resiliency of the spring secondary. The transformer is adapted to conductors of various sizes or diameters by means of split bushings or sleeves, whose inner diameters conform to the size of the conductor. The ratio of the transformer can be changed by removing the spring secondary and substituting one of different diameter or number of turns. Smaller ratio variations may be obtained by means of a contact finger which engages a groove concentric with the periphery of the disk, and contacts with a selected turn of the secondary.

Describing the form of the device which is best adapted for permanent insulation in more detailed terms, a portion of the conductor 6 carr ing the current to be measured is shown. urrounding this conductor is a sleeve 7 which is preferably threaded, and

- which, when once positioned, may be soldered or otherwise secured in place upon the conductor 6.

A disk 8, formed of high grade insulating material such as boro-silicate glass or micalex, is mounted on the sleeve 7 and held in place by the lock-nuts 9. A groove or seat 11 is preferably formed in the periphery of the disk.

Secured within the groove is a pair of hooks 12 which connect to terminals or binding posts 13 and 13. These hooks are placed as close together as is convenient, the hook ends facing each other, and they may be held in position in any convenient manner, 0. g., molded or screwed in place.

1 The secondary winding of the transformer is a helical spring 14, which is stretched into be made by removing one spring and substituting another of different diameter or number of turns, or both. vided, however, for effecting minor ratio changes without changing windings. A recess 16, preferably undercut as shown, is formed in a face of the disk 8 concentric with its periphery. A contact finger 17, preferably of spring material, hooks into this recess and extends over the winding. This finger may be moved to contact w th any selected turn of the secondary.

The meter either be connected to the terminals 13 and 13, as are shown in Figure 1, or it may be connected to the terminal 13 and a terminal 19 mounted on the contact finger.

For temporary or portable use the modification shown in Figures 4 and 5 is advantageous.

In this case a split sleeve or bushing 26 is used, a plurality of these bushings of varying internal diameter being preferably provided to fit different sizes of conductors. The disk in this case is formed in two halves 27 and 28, and fits closely over the divided 7 sleeve 26. The hooks 29 and 31 are both mounted on the half 28 of the disk, and when the spring 32 is stretched in place its resiliency holds the parts of both disk and bushing in position. Minor adjustments in ratio are made with the contact finger 33 which engages the recess 34 in the same manner as in the other modification of the device.

Although the'latter modification does not have the advantage of permanency to the same extent as the first form described, the

split parts may be applied to any conductor ithout opening the circuit of which it forms a part, and it is therefore of'value in taking testreadings in circuits where the permanent installation of an instrument is not warranted. The formation of the parts is such that the spring tension of the secondary serves to aline the device accurately perpendicular to the conductor.

It is obvious that the transformer will operate even though the disk may depart materially from circular form. The advantage of the circular shape lies in its economy of space and material, and in the ease of computation' of the transformer ratio. It is to be understood however, that supporting members of other shapes are equivalentsof the circular disk if usedas" here described.

I claim: 7

1. A current transformer comprising a conductor forming a primary, an insulating" disk mounted on said conductor, and ahelical;

Means are pro-- spring forming a secondary stretched in toroidal form about said disk.

2. A current transformer comprising a conductor forming a primary, an insulating disk mounted on said conductor, a helical spring forming a secondary stretched in toroidal form about said disk, and means on the disk for releasably engaging the ends of said spring.

3. A current transformer comprising a conductor forming a primary, an insulating disk mounted on said conductor and having a seat formed in the periphery thereof, and a helical spring forming a secondary stretched in toroidal form about said disk and positioned by said seat. l

V 4. A current transformer comprising a conductor forming a primary, an insulating disk mounted on said conductor and having a recess concentric with the periphery formed in a face thereof, a resilient toroidal secondary stretched around said disk, and a contact finger engaging said recess and adjustable to contact with a selected turn of said secondary. i i

5. A current transformer adapted for use with a current-carrying conductor comprising a sleeve adapted to fit over the conductor,

an insulating disk mounted on said sleeve,

and a resilient toroidal secondary stretched around the periphery ofsaid disk. 6. A current transformer adapted for use with a current-carrying conductor comprising a divided disk adapted to surround said con ductor, and a helicalspring forming asecondary winding andstretched around said disk to holdthe parts thereof in position. 7. A current transformer adapted for use with a current-carrying conductor comprising a divided disk adapted to surround said conductor, and a helical spring forming a secondary Winding and stretched around said disk and secured to one of the parts thereof to hold the parts in position.

8. A current transformeradapted for use with a current-carrying conductor comprising a split sleeve havingan inner dimension adapted to fit over said conductor, a divided disk fitting over-said sleeve and perpendicular thereto, and a helical spring stretched in toroidal form around said disk and forming a secondary for said transformer and holding the parts of said disk in position.

9. A current transformer adapted for use with a current-carrying conductor compris.

ing a split sleeve having an inner dimension adapted to fit over said conductor, a. divided disk fitting over saidsleeve and perpendicular thereto, a helical spring stretched in toroidal form around said disk and forming a secondary for said transformer and holding the parts of said disk in position, and means on one of the parts of said disk forreleasably engaging the ends of said spring.

'10. A currenhtransformer comprising a conductor forming a rimary, an insulating disk mounted on sai conductor, a helical spring forming a secondary stretched in toroidal form about said disk means on said 5 disk for releasably holding an end of the spring, and a terminal for said secondary connected to said holding means.

In testimony whereof, I have hereunto set my hand.

RALPH M. HEINTZ. 

